Apparatus and Method for Containment of Well Fluids from a Subsea Well Fluid Leak

ABSTRACT

Apparatus and method for containment of well fluids flowing from a subsea well fluid leak feature a containment structure positioned over the well blowout, and an elongated collection conduit supported with an upper end exposed to atmospheric pressure above sea level and a lower end in fluid communication with surrounding sea water over an upper opening of the containment structure. Collected well fluid rises in the elongated conduit due to a lower specific gravity of the well fluid relative to the sea water, and is discharged from the elongated conduit at a location above sea level to a receiving vessel. The open piping system allows for easier installation of the separate containment system and collection conduit, and allows sea water to be displaced from the open lower end of the conduit above the containment structure under filling of the conduit with rising well fluid.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims benefit under 35 U.S.C. 119(e) of U.S.Provisional Patent Application Ser. No. 61/351,560, filed Jun. 4, 2010,the entirety of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to containment or recovery of fluidsescaping a subsea well blowout or leak.

BACKGROUND OF THE INVENTION

The recent occurrence of a major oil spill on Apr. 20, 2010 following anexplosion on the “Deep Water Horizon” well has demonstrated asignificant need for an effective containment means for dealing withsuch potentially disastrous subsea well blowouts.

Regarding this particular event, the defective Blowout Preventer (BOP)is at the sea floor at approximately 5000 feet deep. Within a week ortwo of the explosion, BP built a 100-ton containment house dome andlowered it over top of the largest of three pipe ruptures to try andcapture the oil as it exited from a leaking 21-inch diameter pipe. Atthe top of this dome, they had installed a 12-inch pipe so that theycould suck the oil up unto a waiting tanker at the top. It will beappreciated that any information presented herein on this particularevent, including dimensions and equipment/operation details, are basedon Applicant's best understanding based on information presented invarious media reports, and therefore cannot be guaranteed to be 100%accurate.

This plan failed, perhaps at least in part due to the following issuespondered by the Applicant.

Firstly, apparently methane clathrate crystals formed, plugging the12-inch hole and making the 100-ton dome buoyant. Even if those crystalshadn't formed, it is difficult to imagine how the oil could be suckedout fast enough from a 12-inch pipe at a rate equal to or exceeding theoil entering the containment dome through the 21-inch pipe under highpressure. The negative pressure to suck the oil up could only be oneatmosphere maximum or approximately 14.7 psi reduced pressure at thesuction end.

Secondly, if these methane crystals did form, it would have been due tothe cold water and pressure at the sea bed. This temperature would beapproximately 2° C. to 10° C. and difficult to heat under a closedpiping system.

Applicant has designed a unique solution to address the ongoing spilland which may accordingly be similarly applied to future subsea blowoutsor leaks.

SUMMARY OF THE INVENTION

According to a first aspect of the invention there is provided anapparatus for containment of well fluids flowing from a subsea wellblowout, the apparatus comprising:

-   -   a containment structure comprising a hollow interior space        having upper and lower openings at top and bottom ends of the        hollow interior space, the lower opening being larger than the        upper opening and being positioned over the well blowout to        receive well fluid therefrom;    -   an elongated collection conduit supported with an upper end        thereof at an elevation above sea level and a lower end thereof        submerged at a position over the upper opening of the        containment structure to receive well fluid passing upward        through the containment structure, the upper end of the        collection conduit being exposed to atmospheric pressure and the        lower end of the collection conduit being in fluid communication        with sea water surrounding the containment structure and the        collection conduit;    -   a discharge conduit having an inlet end thereof connected to the        elongated conduit at a position between the sea level and the        upper end of the elongate conduit to fluidly communicate with a        buildup of well fluids above sea level; and    -   a receiving vessel at an outlet end of the discharge conduit        opposite the inlet end thereof.

Preferably the lower end of the collection conduit is open to the seawater surrounding the containment structure and the collection conduitat a location above the lower opening of the containment structure.

Preferably the containment structure comprises a hollow neck extendingupward from the upper opening of the interior space of the containmentstructure, the hollow neck being of smaller diameter than the collectionconduit and extending upward thereinto through the lower end thereof,leaving an annular space at least partially open between the hollow neckand the lower end of the collection conduit to fluidly communicate thecollection conduit with the sea water through said annular space.

Preferably there are provided supports projecting externally from thehollow neck at circumferentially spaced positions thereabout to define aseat upon which the lower end of the collection conduit rests.

Preferably there is provided a control valve installed on the dischargeconduit and operable control a rate at which well fluids are drawn offfrom the buildup thereof above sea level.

The outlet end of the discharge conduit may be positioned at anelevation below the inlet end thereof for gravity fed flow of wellfluids through the discharge conduit to the collection vessel.

Alternatively, a discharge pump may be installed on the dischargeconduit and operable to pump well fluids through the discharge conduitto the collection chamber.

There may be provided a fluid circulation line extending downwardlyinside the collection conduit to proximate the upper opening of thecontainment structure and a circulation pump operable to convey warmingfluid down toward the upper opening of the containment structure throughthe fluid circulation line.

The fluid circulation line may be open at a bottom portion thereofwithin the containment structure.

In such instance, preferably there is provided a circulation outlet pumpon an outlet line connected to the collection conduit below the sealevel, the outlet line being selectively openable to the collectionconduit for operation of the circulation output pump to extract thewarming fluid therefrom.

Preferably an inlet of the fluid circulation line draws from warm seawater proximate sea level under operation of the fluid circulation pump.Preferably the outlet line discharges the warming fluid to sea.

According to a second aspect of the invention there is provided a methodfor containment of well fluids flowing from a subsea well blowout, themethod comprising:

-   -   (a) positioning an elongated collection conduit with an upper        end thereof open to atmospheric pressure at an elevation above        sea level and a lower end of the collection conduit at a        submerged position receiving well fluid from the blowout;    -   (b) allowing well fluid to pass upward through sea water in the        elongated conduit to a surface of the sea water under a rising        effect provided by a lower specific gravity of the well fluid        relative to the sea water;    -   (c) discharging collected well fluid from the elongated conduit        at a location above sea level; and    -   (d) receiving the well fluid discharged from the elongated        conduit at a receiving vessel.

Preferably step (a) comprises positioning a bottom opening of a hollowcontainment structure over the blowout and positioning the lower end ofthe collection conduit over a top opening of an interior space of thehollow containment structure, the top opening of the interior spacebeing smaller than the bottom opening of the containment structure.

Preferably step (a) comprises leaving the lower end of the collectionconduit open to sea water outside the hollow containment structure.

Preferably step (a) comprises positioning the lower end of thecollection conduit around a hollow neck of the containment structurethat projects upward from the upper opening of the interior spacethereof into the collection conduit, and leaving an annular spacebetween the hollow neck and the collection conduit at least partly open.

Preferably step (a) comprises first positioning the hollow containmentstructure and then lowering the collection conduit into place.

Preferably step (a) comprises seating the lower end of the collectionconduit on the containment structure.

Steps (c) and (d) may comprise gravity draining well fluid from thecollection conduit to the vessel.

Alternatively, steps (c) and (d) may comprise pumping well fluid fromthe collection conduit to the vessel.

Preferably step (b) comprises allowing a buildup of well fluid to formatop the surface of the sea water before discharging the collected wellfluid in step (c).

The method may include pumping warm fluid downward through a circulationline in the collection conduit to provide heating proximate the lowerend of the collection conduit.

The warm fluid preferably comprises sea surface water pumped fromproximate the surface of the sea water.

Alternatively, in employment of the invention in colder climates adifferent method of heating the containment structure and collectionconduit may be employed, since warm surface water is not available insuch applications.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings, which illustrate exemplary embodiments ofthe present invention:

FIG. 1 is a schematic illustration of an apparatus for containment of asubsea blowout at a deepwater well, in which an open system conduitextends from a dome placed over the blowout to the surface to allow theless dense oil to rise to the surface through the column of water in theconduit, where the buildup of oil can be drained away to a suitablevessel for transport from the spill site.

FIG. 2 is a schematic illustration of the apparatus of FIG. 1 featuringthe addition of a circulation line through which warm surface water ispumped down through the open system conduit toward the open top of thedome to prevent crystal formation from blocking the conduit.

DETAILED DESCRIPTION

The present invention is designed to contain oil from a subsea blowoutas it exits from the leaking pipe or equipment at the sea bed. Thesolution includes two primary parts in order to deal with thiscontainment problem.

The first part is illustrated in FIG. 1 and essentially deals with howto capture and contain the oil using a containment dome and uprightcollection conduit or vertical riser extending therefrom.

The second part is illustrated in FIG. 2 and deals with warming thecontainment dome and vertical riser if required to deal with or preventmethane clathrate crystals, should the conditions for their occurrencebe present. This may be unlikely during use of a preferably sufficientlylarge pipe for the collection conduit, but a strategy is nonethelessconsidered by the Applicant in case this still poses a problem.

Referring to FIG. 1, a containment dome 12 is a hollow structurefeaturing peripheral wall sections 14 closing around a central axis ofthe structure, and an upward tapering domed or inverted funnel-likecover 16 fixed atop the peripheral wall to narrow the hollow interiorspace of the dome 12 from a larger diameter at the peripheral wall to asmaller diameter at the top of the cover, where a central opening isdisposed at what would otherwise be the peak of the cover. The openbottom of the containment dome 12, bound by the peripheral wall sections14 thereof, is seated on the sea bed around the rupture from which theoil is leaking so that the oil spills into the hollow interior of thecontainment dome through the open bottom thereof. The dome is to bepositioned above the leak in a manner suitable to capture as much oil aspossible, which may or may not be accomplished by seating on the seafloor depending on the type and location of leaking equipment. Forexample, in other situations, it may be more appropriate to suspend thedome at a height above the sea bed to capture leakage from a rupturedpoint upward therefrom.

A pipe fixed atop the cover 16 of the containment dome 12 around thecentral opening in the cover projects upward therefrom to form aneck-like hollow extension 18 communicating with the containment dome'shollow interior space beneath the cover 16. The extension extendsvertically upward from the cover 16 on the central axis of thecontainment structure and is open at its top end.

After placement of the containment dome 12 above the leak, a length ofpiping of inner diameter greater than the outer diameter of theneck-like extension 18 of the containment dome 12 is lowered into thesea from the surface to form a collection conduit 20 from thecontainment dome 12 to the surface. The open bottom end of thecollection conduit 20 is lowered over the top end of the neck-likeextension 18 to sit atop a series of external projections 22 provided onthe neck 18 at positions spaced around the circumference thereof toproject radially outward therefrom. These projections 22 are positionednearer the cover 16 of the containment dome 12 than the upper end of theneck 18 so that the neck's length lies substantially within thecollection conduit 20. Except at the spaced apart projections 22, anannulus between the neck 18 and the conduit 20 is left open at thebottom end of the collection conduit 20 to communicate with the seawater externally surrounding the containment dome 12 and the collectionconduit 20.

The top end of the collection conduit 20 is disposed well above the sealevel surface and is left open to the atmosphere to cooperate with theopen bottom of the conduit to define an open system conduit extendingfrom the containment dome 12 to above the surface. During lowering ofthe collection conduit 20 onto the containment dome 12, sea wateroccupies the conduit from the open lower end thereof up to the sea levelsurface. Once the collection conduit is in place, the oil from the leakflows upward through the containment dome 12 and into the collectionconduit 20 via the neck 18 of the dome. The lower density of the oilrelative to the sea water causes the oil to automatically rise throughthe vertical column of water in the collection conduit up to the surface

At an elevation above the water's surface, an oil discharge line orconduit 24 connects to the collection conduit 20 to fluidly communicatetherewith. A control valve 26 installed on the discharge line 24 isoperable to control a degree of opening and closing of the dischargeline 24. When oil rising through the collection conduit 20 has built upabove the sea level surface in an amount sufficient to at least reachthe discharge line 24, the control valve 26 is in an open state and thusallows the oil to pass through the discharge line 24 and into a vessel28 positioned at the outlet of the discharge conduit 24 to receive thecollected oil therefrom. The annular space between the two pipes formingthe containment structure neck 18 and the collection conduit 20 isdimensioned to be large enough in area to handle all the water beingdownwardly displaced from the collection conduit by rising oilintroduced to the system from the leak during this initial stage ofbuilding up oil at a top portion of the subsea column to build up to thedraw-off level of the discharge conduit.

The vessel is preferably provided in the form of a ship or othertransportable vessel that can be used to transport the received oil awayfrom the offshore site. In the illustrated embodiment, the dischargeconduit 24 is gravity operated, with its outlet end disposed at a lowerelevation that its connection to the collection conduit 20 so that oilbuilt up in the collection conduit to the discharge conduit willautomatically drain therethrough to the vessel. Other embodiments mayemploy a discharge pump on the discharge conduit to pump collected oilto the receiving vessel.

Should temperatures and pressures at the containment dome 12 or lowerportions of the collection conduit 20 be such that methane clathratecrystals form to an extent plugging the flow to the surface, even wherelarge piping is used with the intention of avoiding such problems, thenextra measures can be taken to prevent or alleviate such plugging, asnow will be described with reference to FIG. 2.

Turning to FIG. 2, a fluid circulation line 30 has an inlet 30 adisposed within the sea water a shod distance below the surface thereof,and has a pump 32 installed on the line to draw warm surface water intothe line through the inlet and pump it onward through the line into thecollection conduit 20, for example through the open top end thereofdisposed above sea level. The circulation line 30 passes downwardthrough the collection conduit 20 to proximate the lower end thereof,and in the illustrated embodiment, slightly past the bottom end of thecollection conduit 20 so as to depend into the interior space of thecontainment dome 12. A lower end portion of the circulation line 30 isopen at one or more locations therealong.

Should a heating function be required to remove or prevent crystalplugging of the upper opening of the dome's interior space or the dome'sextension neck, the circulation line is run into the collection conduit(if not having been previously deployed or installed therein), acirculation shut-off valve 34 on the circulation line is opened, and thecirculation pump 32 is activated to pump the warm surface water throughthe circulation line down to the bottom of the collection conduit 20,where this warmer water exits the circulation and provides heat toremove or prevent crystal formation at these narrowest points in theflow passage from the blowout to the surface through the containmentdome and collection conduit.

While this warm water is being pumped in to remove a plug,simultaneously a circulation outlet pump 36 on an outlet line 38connected to the collection conduit a short distance below the seallevel surface may be operated with a shut-off valve 40 on this lineopened in order to pump sea water out of the collection conduit (thecollection conduit containing only sea water at this point in time dueto the plugging of further oil flow through the system due to theplugging at the containment dome) and back to the sea at a significantdistance from the circulation line inlet 30 a. The circulation pumpsthus keep circulating a fresh supply of warm surface water through theopen system to warm the interior of the collection conduit 20 to removeany clogging thereof. When the circulation is not required, thecirculation pumps 32, 36 are shut down and shut off valves 34, 40 on thecirculation lines are closed.

The use of an open piping system above the dome between the two sizes ofpipes presents advantages over known subsea containment systemsemploying a dome or inverted funnel coupled to an above surfacereceiving or processing vessel by a closed piping system.

At the start of the operation, as leaking oil gets added in the verticalriser pipe, sea water in the riser pipe has to be displaced. If theriser or collector pipe was to be solidly connected to the dome in aclosed fashion, this displaced water would have to be released below thedome, forcing oil in the dome downwards in the dome and causing the oilto escape to the sea. With the system having the riser pipe open to thesea above the dome, water is allowed to leave the riser pipe column viathe space between the two pipes and oil should not escape at all. Thisopening always allows the vertical column pressure to equalize with thesea irrespective of how much oil is entering the column and irrespectiveof how much oil is removed at the top of the column.

Another advantage to this system is that the dome can be lowered and putin place completely separate from the vertical column pipe, potentiallymaking the installation much easier from the top. This way, it may bethat no work has to take place at the bottom of the sea.

Furthermore, if for some reason, a miscalculation of the amount of oiland gas flow coming out was made, causing the neck of the dome to beundersized, or if methane clathrate crystals formed due to temperatureor pressure, this problem would be obvious as soon as the dome is put inplace, and remedial steps could be taken prior to manufacturing andinstalling the long vertical pipe column.

As an example of how the present invention may be implemented, theinstallation and use of the apparatus is now described as follows interms of the spill at the Deepwater Horizon location in the Gulf ofMexico. The dimensions used in the following description are exemplaryonly, and are not intended to limit the scope of the present invention,nor even limit dimensions that will result in a functional embodiment inthis particular exemplary context. All pipe sizes shown may be increasedin size or even reduced to deal with larger spills depending onanticipated flows.

Part A (FIG. 1)

-   -   1—Raise the existing 100-ton containment dome to the top surface        and equip it with a much larger pipe at the top to replace the        12-inch pipe that is there and define the neck-like extension of        the above described containment dome. This steel pipe may be        approximately 36 inches diameter, which presents approximately 9        times the flow area of the 12-inch pipe and 3 times the area of        the 21-inch ruptured pipe. This new 36-inch pipe could protrude        approximately 30 feet above the top of the dome. At a short        height above the top of the dome, for example approximately 5        feet, pieces of steel would be welded to the four exterior sides        of the 36-inch pipe to project outward therefrom. A larger pipe        to be slipped over the 36-inch pipe to define the collection        conduit could therefore rest on these four welded pieces of        steel. This allows the vertical piping to be an open piping        system rather than a closed piping system, while still        preventing the oil from escaping downwards through the cavity        between the two pipes. In this way, the pressures on the        exterior and interior of all piping remain in balance        facilitating greatly the implementation of strategies without        concerns of high pressures.    -   2—The dome can now be lowered over top the leak to observe if        the oil exits through the top of the 36-inch pipe. If it does,        than the rest of the plan should work successfully without        having to implement the additional fluid-circulation part of        FIG. 2, meaning that crystals have not formed and the oil can        simply rise through the pipe due to a lighter specific gravity        than the sea water's specific gravity, which is approximately        1.025.    -   3—A larger piece of pipe with an inner diameter larger than the        outer diameter of the 36-inch pipe, for example approximately 4        inches larger or another possibly greater size large enough to        handle the expected rate of water displaced downward by rising        oil leakage flow when collected oil is not being drawn off above        the surface, is manufactured and slipped over top of the 36-inch        pipe to rest on the welded steel pieces mentioned in item 1        above. This larger pipe would extend from the top of the        containment dome to the sea surface to define the collection        conduit. As examples, this pipe could be a steel pipe, or even        PVC pipe to make it easier to fabricate. A PVC pipe can easily        be welded at 20 ft. intervals with PVC cement glue. For example,        200 ft. of steel pipe could be used for the lower portion of the        conduit, and the rest could be PVC pipe. Due to the ocean        currents which may pull the pipe sideways though, such PVC pipe        may need to be encircled with steel cables which are used to        lower the steel pipe to the bottom and hold it from falling.        This way, there is sufficient weight from the steel pipe to keep        the lowering cables tight to keep the vertical PVC pipe straight        and upright. If no crystals were formed as mentioned in item 2        above, the oil should simply rise to the surface.    -   4—With oil rising to the surface naturally because of its lower        specific gravity, the larger pipe would need to extend a        considerable distance above the sea surface, for example to        approximately 50 feet. A pipe with a control valve would be        connected to this larger vertical pipe above the sea surface,        for example by some 30 ft., to act as the discharge conduit        capturing the rising oil and allowing it to simply flow to a        waiting tanker vessel via gravity or pump suction. Due to the        upward force of the weight of the water at the bottom of the sea        entering the open piping system at the bottom and pushing up the        oil, a column of oil and water results in this larger pipe. The        oil will rise to the upper portion of the column and extend at a        fairly great distance above the sea surface. For example, from        initial calculation based on an assumed oil specific gravity of        0.90, maintaining a top oil-filled portion of the        below-sea-surface column as 6% of the overall column height        after allowing sufficient initial oil flow to reach this buildup        of oil before opening the discharge conduit will result in the        oil rising approximately 42 ft. above the surface of the sea due        to the heavier sea water pushing it up in the column. By        controlling the rate of oil that exits this vertical collection        pipe via the control valve on the discharge pipe, the amount of        oil in the column is controlled as a percentage of the sea water        in the column. This balance can be achieved by simply using a        level controller and sensor to control the oil outlet valve to        maintain a constant oil level in the vertical riser.

Part B (FIG. 2)

-   -   5—If the oil doesn't come through due to crystals forming, even        though this may be very unlikely due to the relatively large        size used in this example, then warming of the water inside the        containment dome to a higher temperature can be employed to        address this issue. Apparently, crystals have never been        observed to form above approximately 10° C. at the seabed        pressure. Fortunately, there is a virtually infinite supply of        warm water at the sea surface. The water temperature at this        time of year in the region concerned is approximately 30° C. By        pumping this warm sea water to the bottom through a smaller        pipe, for example 6 or 8-inch diameter lowered inside the larger        42-inch pipe, and at the same time pumping out sea water from        this larger vertical pipe at the top portion thereof at a level        near the sea surface, for example about 10 ft. below, and just        simply pumping this water back to the sea; the water inside the        containment dome and the vertical riser pipe can be warmed up        significantly. It is estimated that pumping at a rate of        approximately 1,000 usgpm, it would take about 6 hours to        completely change the water in this larger vertical pipe,        meaning that now the temperature inside the containment dome and        the vertical riser pipe may approach somewhere between 20° C.        (due to heat losses in the pipe) and 30° C. PVC pipe would        lessen this temperature loss as compared to steel pipe. As        schematically shown in FIG. 2, this warm supply pipe may be        capped at the bottom with drilled holes in the pipe sides in the        bottom 30 feet of piping. Water would escape at this drilled        bottom portion of this warm supply pipe to heat the dome and        vertical riser pipe. This allows a free exchange of warm sea        water throughout the vertical column without having cold water        come in from the bottom of the pipe. This would enable the oil        to rise to the surface and all water pumping would cease once        the oil comes up the vertical riser column and arrives at the        top.    -   6—This containment process can be maintained indefinitely until        the well can be plugged permanently via the extra intercepting        well that BP is presently working on, which will take about        three months from the start of drilling operations. Other leaks        can be contained in the same manner. As well, for future        drilling, this approach can be repeated as many times as needed        and provide the oil industry and the government a new and a        rather foul proof way of containing spills without having to try        and work at ocean depths to contain spills. This approach also        uses basic physics and mechanics that doesn't depend on        sophisticated technology and is therefore very reliable. The        approach makes it easy for the public and various politicians to        understand and approve the ultimate back-up plan. Equipment        could be built early and stored for use in case of emergencies        arising from similar spills in the future.

While the illustrated embodiment is left entirely open to the atmosphereat the top end of the collection conduit piping above sea level, it willbe appreciated that methane and other gases may be given off at thisopen top end of the system, and alternate embodiments may additionallyfeature equipment for capturing, flaring or burning such released gaseswhile maintaining an open conduit system that is exposed to atmosphericpressure above sea level. Also, while having the system open at thetransition between the collection conduit and the containment structurehas advantages, other embodiments may alternatively have the bottom“opening” of instead formed by open space left between the sea bed andparts of the containment dome wall sections supported thereon.

Since various modifications can be made in my invention as herein abovedescribed, and many apparently widely different embodiments of same madewithin the spirit and scope of the claims without departing from suchspirit and scope, it is intended that all matter contained in theaccompanying specification shall be interpreted as illustrative only andnot in a limiting sense.

1. An apparatus for containment of well fluids flowing from a subseawell fluid leak, the apparatus comprising: a containment structurecomprising a hollow interior space having upper and lower openings attop and bottom ends of the hollow interior space, the lower openingbeing larger than the upper opening and being positioned over the wellblowout to receive well fluid therefrom; an elongated collection conduitsupported with an upper end thereof at an elevation above sea level anda lower end thereof submerged at a position over the upper opening ofthe containment structure to receive well fluid passing upward throughthe containment structure, the upper end of the collection conduit beingexposed to atmospheric pressure and the lower end of the collectionconduit being in fluid communication with sea water surrounding thecontainment structure and the collection conduit; a discharge conduithaving an inlet end thereof connected to the elongated conduit at aposition between the sea level and the upper end of the elongate conduitto fluidly communicate with a buildup of well fluids above sea level;and a receiving vessel at an outlet end of the discharge conduitopposite the inlet end thereof.
 2. The apparatus of claim 1 wherein thelower end of the collection conduit is open to the sea water surroundingthe containment structure and the collection conduit at a location abovethe lower opening of the containment structure.
 3. The apparatus ofclaim 1 wherein the containment structure comprises a hollow neckextending upward from the upper opening of the interior space of thecontainment structure, the hollow neck being of smaller diameter thanthe collection conduit and extending upward thereinto through the lowerend thereof, leaving an annular space at least partially open betweenthe hollow neck and the lower end of the collection conduit to fluidlycommunicate the collection conduit with the sea water through saidannular space.
 4. The apparatus of claim 3 comprising supportsprojecting externally from the hollow neck at circumferentially spacedpositions thereabout to define a seat upon which the lower end of thecollection conduit rests.
 5. The apparatus of claim 1 comprising acontrol valve installed on the discharge conduit and operable control arate at which well fluids are drawn off from the buildup thereof abovesea level.
 6. The apparatus of claim 1 further comprising a fluidcirculation line extending downwardly inside the collection conduit toproximate the upper opening of the containment structure and acirculation pump operable to convey warming fluid down toward the upperopening of the containment structure through the fluid circulation line.7. The apparatus of claim 6 wherein the fluid circulation line is openat a bottom portion thereof within the containment structure.
 8. Theapparatus of claim 7 comprising a circulation outlet pump on an outletline connected to the collection conduit below the sea level, the outletline being selectively openable to the collection conduit for operationof the circulation output pump to extract the warming fluid therefrom.9. The apparatus of claim 8 wherein the outlet line discharges thewarming fluid to sea.
 10. The apparatus of claim 6 wherein an inlet ofthe fluid circulation line draws from warm sea water proximate sea levelunder operation of the fluid circulation pump.
 11. A method forcontainment of well fluids flowing from a subsea well fluid leak, themethod comprising: (a) positioning an elongated collection conduit withan upper end thereof open to atmospheric pressure at an elevation abovesea level and a lower end of the collection conduit at a submergedposition receiving well fluid from the blowout; (b) allowing well fluidto pass upward through sea water in the elongated conduit to a surfaceof the sea water under a rising effect provided by a lower specificgravity of the well fluid relative to the sea water; (c) dischargingcollected well fluid from the elongated conduit at a location above sealevel; and (d) receiving the well fluid discharged from the elongatedconduit at a receiving vessel.
 12. The method of claim 11 wherein step(a) comprises positioning a bottom opening of a hollow containmentstructure over the blowout and positioning the lower end of thecollection conduit over a top opening of an interior space of the hollowcontainment structure, the top opening of the interior space beingsmaller than the bottom opening of the containment structure.
 13. Themethod of claim 1 wherein step (a) comprises leaving the lower end ofthe collection conduit open to sea water outside the hollow containmentstructure.
 14. The method of claim 11 wherein step (a) comprisespositioning the lower end of the collection conduit around a hollow neckof the containment structure that projects upward from the upper openingof the interior space thereof into the collection conduit, and leavingan annular space between the hollow neck and the collection conduit atleast party open.
 15. The method of claim 11 wherein step (a) comprisesfirst positioning the hollow containment structure and then lowering thecollection conduit into place.
 16. The method of claim 15 wherein step(a) comprises seating the lower end of the collection conduit on thecontainment structure.
 17. The method of claim 11 wherein step (b)comprises allowing a buildup of well fluid to form atop the surface ofthe sea water before discharging the collected well fluid in step (c).18. The method of claim 11 comprising pumping warm fluid downwardthrough a circulation line in the collection conduit to provide heatingproximate the lower end of the collection conduit.
 19. The method ofclaim 18 wherein the warm fluid comprises sea surface water pumped fromproximate the surface of the sea water.